A polyoxyalkylene compound produced by ring-opening polymerization of an alkylene oxide such as propylene oxide or ethylene oxide to an initiator having at least one active hydrogen-containing functional group to which an alkylene oxide is reactive, is industrially useful, for example, as a polyol component to be used in the polyurethane industry or as a surfactant and a starting material thereof. Such a polyoxyalkylene compound may be prepared to have various characteristics by selecting the initiator to be used.
As the initiator, a compound having a hydroxyl group is the commonest compound. As a catalyst for the ring-opening polymerization of an alkylene oxide, an alkali catalyst such as an alkali metal hydroxide is widely employed. The alkali catalyst reacts with a hydroxyl group of the initiator or with a hydroxyl group formed afresh by a reaction of an alkylene oxide, to form an alkali metal alkoxide, and this alkali metal ion is believed to serve as a catalyst.
A polyoxyalkylene compound obtainable by ring-opening polymerization of an alkylene oxide to an initiator having an organopolysiloxane structure or to an initiator having a fluorinated hydrocarbon group, is useful as a starting material for various synthetic resins, as a modifier or as an additive, and it is expected to provide such characteristics as improvement of weather resistance or water resistance, a tack-reducing effect or improvement of self-releasing properties. However, when such a highly hydrophobic initiator is used, the ring-opening addition reaction of an alkylene oxide to the active hydrogen-containing functional group of the initiator tends to be remarkably disadvantageous with the conventional alkali catalyst.
When an alkali catalyst is added to a highly hydrophobic initiator, the compatibility of the initiator and the alkali catalyst is poor, and the two do not easily react to each other. Therefore, the hydroxyl group of the initiator tends to be hardly converted to an alkali metal alkoxide, and an alkylene oxide is hardly reactive to such a hydroxyl group. Therefore, the alkali catalyst itself such as the alkali metal hydroxide or the existing water is likely to act as an initiator, whereby it happens that a polyoxyalkylene glycol which is not bonded to the highly hydrophobic initiator, will form as a by-product. Further, there is a problem that if the temperature in the system is brought to a high level of at least 100.degree. C. in the presence of an alkali metal hydroxide, a decomposition reaction of the organopolysiloxane is likely to occur. Further, there is a compound instable to an alkali catalyst, such as a partially fluorinated alkanol.
It is known to use an acid catalyst such as boron trifluoride instead of the alkali catalyst. However, use of an acid catalyst has a problem such that a homopolymer of the alkylene oxide is likely to be formed as a byproduct, and it is difficult to obtain a polyoxyalkylene compound of a high molecular weight.